Objective
The aim of this study was to analyze significant motion predictors in patients with discogenic and facetogenic back pain confirmed by diagnostic injections and to see confounders which influence motion predictors.
Methods
Medial branch block and epidural steroid injection were used for facetogenic and discogenic midline pain. Transforaminal epidural steroid injection was selected for discogenic lateralized back pain. Positive response was defined as over 75% pain relief. Sixty-four patients (facetogenic pain, 45 bilateral or 9 unilateral, 82% pain relief ), Sixty-three patients (discogenic midline pain, 83%), and twenty-three patients (discogenic lateralized pain, 85%) had been enrolled prospectively in one institution between June 2010 and October 2013. Motion provocation tests were conducted during standing, sitting, flexion, extension, lateral bending, rotation, and extension with rotation for the detection of motion predictors. A self-weighted grade system was applied for pain provocation. Confounders such as age, sex, facet joint degeneration, flexion pain, grade of protrusion, circumferential annular tear, transverse annular tear, and spino-pelvic parameters were assessed to find the influence on motion predictors.
Results
In patients with facetogenic pain, pain provocation was prominent during standing (p=0.006), extension (p=0.052), rotation (p=0.000), and extension with rotation (p=0.000). In those with discogenic midline pain, more pain generated during flexion (p=0.000) and sitting (p=0.044). The difference in spino-pelvic parameters between two pain groups was not observed. The difference between discogenic midline and lateralized pain occurred during flexion (midline, p=0.046) and lateral bending (lateralized, p=0.057). Similarly, flexion (p=0.068) and lateral bending (p=0.067) might be also insignificant but helpful predictors to differentiate discogenic lateralized pain from facetogenic lateralized pain. For facetogenic pain, there were significant confounders as follows; standing (facet capsule enhancement, pelvic incidence), sitting (sex), extension (spino-pelvic parameters), lateral bending (pelvic tilt), rotation (age, sex, arthritis, facet capsule enhancement, pelvic tilt). Extension with rotation showed relatively less changes. For discogenic pain, a lake type circumferential tear generated less flexion pain and more extension pain. A superior transverse tear influenced sitting, extension, and lateral bending. A protrusion without a transverse tear increase flexion pain. Higher pelvic incidence and pelvic tilt generated more extension and extension with rotation pain. Among motions, sitting was not influenced by most probable confounders.
Conclusion
Predictors of facetogenic pain were extension with rotation, rotation, standing, extension, and lateral bending in order of probability. Flexion and sitting may be predictors of discogenic midline pain. Flexion and lateral bending may be predictors favoring discogenic lateralized pain compared with facetogenic pain. However, these motions may be vulnerable to parameters such as age, sex, facet arthritis, facet enhancement, circumferential or transverse tear, and spino-pelvic parameters. Considering the confounders’ effect, predictors were likely to be extension with rotation for facetogenic pain, sitting for discogenic midline pain, flexion and lateral bending for discogenic lateralized pain compared with facetogenic pain. These points should be considered in making a diagnosis during the physical examination in the outpatient clinic.

Discectomy or fusion have been a gold standard of the treatment for discogenic back pain. Since mid 1950s, spine surgeons have introduced the concept of arthroplasty for the management of low back pain. The current technologies are total disc replacement (TDR), posterior dynamic stabilization (PDS), interspinous process. Although many studies have reported their efficacy and safety, there are still lacking high-quality evidence. It is also not proven that these technologies are superior to spinal fusion in preventing the adjacent segment disease. Second generation TDR is newly developed technology. The current TDR could allow the motion of flexionextension and lateral bending, but it did not have the capacity to bear the axial compressive force. Second generation TDR placed the shock-absorption materials that can endure the compressive force. The current TDR was performed through the anterior approach, which is invasive and necessitates the removal of anterior longitudinal ligament. To overcome these disadvantages, TDR through lateral approach was developed. Various type of nucleus replacement technologies have been introduced with theoretical advantages over TDR such as less invasiveness, stable segmental motion and preservation of disc height. However, some of them had critical problems such as the migration and subsidence of implanted prosthesis. Total facet replacement arthroplasty was developed to overcome both the adjacent segment disease after fusion and the instability after posterior decompression. Because most of reports about total facet replacement arthroplasty are based on the results from the animal or cadaveric study, the long-term human trial is required. New technologies regarding motion preservation spinal surgery have been introduced, shifting paradigm in spinal care. Even though various attempts have been made in the field of spine surgery, the fact is that all of these attempts do not succeed due to paucity of better clinical outcomes. Thus, well designed long-term studies are required to prove their safety and efficacy, showing “superiority”, not just “no inferiority” to the traditional treatments.